Steering systems utilize revolute joints and parallelogram-style linkages to convert the rotational motion of the steering wheel into the linear motion needed to turn the wheels. In the case of recirculating ball steering systems, rotation of a pitman arm is converted into generally-linear movement of a track rod or relay rod. The relay rod is coupled through linkages to turn the wheels and therefore turn the vehicle.
The steering system plays a role in total vehicle handling. Under steer, steering effort, steering sensitivity, and other performance characteristics are affected by the geometry and compliance of the steering system and its components. Parallelogram-style steering systems are generally built from rigid components.